BMI-related microstructural changes in the tibial subchondral trabecular bone of patients with knee osteoarthritis.

Overweight is a risk factor for osteoarthritis on the knees. Subchondral trabecular bone (SCTB) densification has been shown to be associated with cartilage degeneration. This study analyzed the microarchitectural changes in the SCTB of tibial plateaus to validate the hypothesis that the degree of remodeling is correlated with a patient's body weight. Twenty-one tibial plateaus were collected during total knee arthroplasty from 21 patients (15 women and 6 men). These patients had a mean age of 70.4 years (49-81), mean weight of 74.7 kg (57-93) and mean body mass index (BMI) of 28.4 kg/m2 (21.3-40.8). One cylindrical plug was harvested in the center of each tibial plateau (medial and lateral). Micro-CT parameters (7.4 μm resolution) were determined to describe the SCTB structure. On the medial plateau, there were significant correlations between BMI and bone volume fraction BV/TV (r = 0.595, p = 0.004), structure model index SMI (r = -0.704 p = 0.0002), trabecular space Tb.Sp (r = 0.600, p = 0.04) and trabecular number Tb.N (r = 0.549, p = 0.01). SCTB densification during osteoarthritis is associated with a reduction in its elastic modulus, which could increase cartilage stress, and accelerate cartilage loss. SCTB densification has been shown to precede cartilage degeneration. The correlation of SCTB microarchitecture and body weight may explain why knee osteoarthritis is more common in overweight or obese patients.